Anatomically, an eye may be divided into two distinct parts—an anterior segment and a posterior segment. The anterior segment includes a lens and extends from an outermost layer of the cornea (the corneal endothelium) to the posterior surface of the lens capsule. The posterior segment includes the portion of the eye behind the lens capsule. The posterior segment extends from an anterior hyaloid face (part of the vitreous body) to the retina, with which a posterior hyaloid face is in direct contact. The posterior segment is much larger than the anterior segment and includes retinal pigment epithelium and choroid, both under the retina.
The posterior segment includes the vitreous body, a clear, gel-like substance composed of approximately 1% collagen and sodium hyaluronate and 99% water that makes up approximately two-thirds of the eye's volume. The anterior boundary of the vitreous body is the anterior hyaloid face, which touches the posterior capsule of the lens. The posterior boundary of the vitreous body is the posterior hyaloid face, which is in contact with the retina. The vitreous body is not free flowing like the aqueous humor and has normal anatomic attachment sites. One of these sites is the vitreous base, which is an approximately 3-4 mm wide band that overlies the ora serrata. The optic nerve head, macula, and vascular arcade are also sites of relative attachment. The vitreous body's major functions are to hold the retina in place, maintain the integrity and shape of the globe, absorb shock due to movement, and to give support for the lens posteriorly.
Various surgical procedures, called vitreo-retinal procedures, are commonly performed in the posterior segment of the eye to treat a number of serious conditions affecting the posterior segment. Vitreo-retinal procedures treat conditions such as diabetic retinopathy and diabetic vitreous hemorrhage, macular hole, epimacular membrane, vitreomacular traction, retinal detachment, trauma, and many other ophthalmic conditions. A surgeon may perform vitreo-retinal procedures with a microscope and special lenses designed to provide a clear image of the posterior segment. Several small incisions (approximately a millimeter in length) may be made on the sclera at the pars plana to allow the surgeon to insert microsurgical instruments into the posterior segment. For example one or more fiber optic light sources may be inserted to illuminate inside the eye, an infusion line may be inserted to maintain the eye's shape during surgery, and vitrectomy probe may be inserted to cut and remove the vitreous body.
During vitreo-retinal procedures, proper illumination of the inside of the eye is important. In certain conventional systems, a light source, such as a halogen tungsten lamp or high pressure arc lamp (metal-halides, Xe), may be used to produce light that is coupled to an optical fiber (e.g., via one or more lenses, mirrors, and/or attenuators), and the optical fiber may be inserted into the eye to provide the illumination. One disadvantage of these conventional systems is the relatively short life of halogen tungsten lamps and high pressure arc lamps, leading to the need to exchange lamps several times over the life of the system. Additionally, illumination provided by a single, dedicated illumination fiber may be insufficient, particularly as the diameter of such fibers decreases. The present disclosure is directed to an illumination system that addresses one or more of these disadvantages.